Using Spatial Diversity to Improve the Confidentiality of Atmospheric Free Space Optical Communication

Free space optical communication through the atmosphere has the potential to provide secure, low-cost, rapidly deployable, dynamic, data transmission at very high rates. Despite the ability for free space optical technology to transmit a narrow beam of light to a specific destination, it is still possible for an eavesdropper to gather light and decode information intended for another user. This paper addresses the use of spatial diversity to improve confidentiality, thereby impeding potential eavesdroppers. We find that spatial diversity with coherent detection and wavefront predistortion based on turbulence state feedback is an effectively technique to improve the confidentiality of free space optical communication.